Android：Camera Asynctask with Preview Callback [英] Android: Camera Asynctask with Preview Callback
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问题描述
我已经设法使用自定义滤镜（灰度，色调等）进行相机预览。此自定义过滤器通过操作RGB数组，然后将其绘制回画布，然后在表面视图中显示，从而应用预览回调。
I've managed to get camera preview with custom filter (grayscale, hue, etc) working. This custom filter is applied with preview callback by manipulating the array of RGB and then drawing it back to a canvas then display it at the surface view.
这样做的缺点是我得到一个非常低的FPS。有了这个低FPS，它在UI线程中做太多的工作，如果我不这样做在后台线程使用Asynctask。所以我试图使用Asynctask的相机操作（我的主要目的是让UI仍然工作完美，即使有重的工作从相机预览回调）。
The drawback from this is I get a very low FPS. With this low FPS, it's doing too much work in the UI thread if I don't do this in the background thread using Asynctask. So I tried to use Asynctask for the camera operation (my main purpose is to get the UI still working perfectly even with the heavy work from the camera preview callback).
但即使我使用Asynctask，它没有帮助太多。所以我想知道是我的实现是错误的，还是因为即使使用asynctask的UI线程仍然会受到影响？
But even after I used Asynctask, it didn't help much. So I am wondering is it my implementation is wrong or is it because even with asynctask the UI thread will still be affected?
我的代码片断如下：
CameraActivity.java
CameraActivity.java
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d("ACTIVITY_LIFECYCLE","CameraActivity: onCreate");
setContentView(R.layout.camera_layout);
}
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
@Override
protected void onResume() {
Log.d("ACTIVITY_LIFECYCLE","CameraActivity: onResume");
if(preview == null){
preview = new CameraPreviewAsync(this,camera);
preview.execute();
}
super.onResume();
}
@Override
protected void onPause() {
Log.d("ACTIVITY_LIFECYCLE","CameraActivity: onPause");
if(preview!=null){
preview.cancel(true);
camera = preview.getCamera();
if(camera!=null){
camera.stopPreview();
camera.setPreviewCallback(null);
camera.release();
camera = null;
preview.setCamera(camera);
}
preview = null;
}
super.onPause();
}
@Override
public void onDestroy(){
Log.d("ACTIVITY_LIFECYCLE","CameraActivity: onDestroy");
super.onDestroy();
}
CameraPreviewAsync.java：
CameraPreviewAsync.java:
private final String TAG = "CameraPreviewAsync";
private CameraActivity camAct;
private Camera mCamera;
private int cameraId;
private SurfaceView mSurfaceView;
private SurfaceHolder mHolder;
private boolean isPreviewRunning = false;
private int[] rgbints;
private int width;
private int height;
private Bitmap mBitmap;
public CameraPreviewAsync(CameraActivity act, Camera cam){
this.camAct = act;
this.mCamera = cam;
this.mSurfaceView = (SurfaceView) act.findViewById(R.id.surfaceView);
}
public void resetSurface(){
if(mCamera!=null){
mCamera.stopPreview();
mCamera.setPreviewCallback(null);
mCamera.release();
mCamera = null;
}
int tempId = R.id.surfaceView;
RelativeLayout buttonBar = (RelativeLayout) camAct.findViewById(R.id.buttonBar);
((RelativeLayout) camAct.findViewById(R.id.preview)).removeAllViews();
SurfaceView newSurface = new SurfaceView(camAct);
newSurface.setId(tempId);
RelativeLayout.LayoutParams layParams = new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
layParams.alignWithParent = true;
newSurface.setLayoutParams(layParams);
((RelativeLayout) camAct.findViewById(R.id.preview)).addView(newSurface);
((RelativeLayout) camAct.findViewById(R.id.preview)).addView(buttonBar);
}
@Override
protected void onPreExecute() {
//Things to do before doInBackground executed
Log.d(TAG,"onPreExecute");
RelativeLayout.LayoutParams layParams = new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
layParams.alignWithParent = true;
mSurfaceView.setLayoutParams(layParams);
//Check number of camera in the device, if less than 2 then remove swap button
if (Camera.getNumberOfCameras() < 2) {
((RelativeLayout) camAct.findViewById(R.id.buttonBar)).removeViewAt(R.id.cameraSwap);
}
//Opening the camera
cameraId = findBackFacingCamera();
if (cameraId < 0) {
cameraId = findFrontFacingCamera();
if (cameraId < 0)
Toast.makeText(camAct, "No camera found.", Toast.LENGTH_LONG).show();
else
mCamera = Camera.open(cameraId);
} else {
mCamera = Camera.open(cameraId);
}
//invalidate the menu bar and show menu appropriately
camAct.invalidateOptionsMenu();
// get Camera parameters and set it to Auto Focus
if(mCamera!=null){
Camera.Parameters params = mCamera.getParameters();
List<String> focusModes = params.getSupportedFocusModes();
if (focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {
// set the focus mode
params.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
// set Camera parameters
mCamera.setParameters(params);
}
}
super.onPreExecute();
}
@Override
protected Void doInBackground(Void... params) {
//Things to do in the background thread
Log.d(TAG,"doInBackground");
mHolder = mSurfaceView.getHolder();
mHolder.addCallback(surfaceCallback);
return null;
}
@Override
protected void onPostExecute(Void values) {
//Things to do after doInBackground
Log.d(TAG,"onPostExecute");
}
@Override
protected void onCancelled(){
super.onCancelled();
}
/*
* ************************************************************************************
* SURFACEHOLDER CALLBACK
* ************************************************************************************
*/
SurfaceHolder.Callback surfaceCallback = new SurfaceHolder.Callback() {
@Override
public void surfaceCreated(SurfaceHolder holder) {
Log.d(TAG,"surfaceCreated!!");
if(CameraActivity.filterMode == CameraActivity.NORMAL_FILTER){
try {
if (mCamera != null) {
mCamera.startPreview();
mCamera.setPreviewDisplay(holder);
}else{
Log.d(TAG,"CAMERA IS NULL in surfaceCreated!!");
}
} catch (IOException exception) {
Log.e(TAG, "IOException caused by setPreviewDisplay()", exception);
}
}else{
synchronized(mSurfaceView){
if(isPreviewRunning){
return;
}else{
mSurfaceView.setWillNotDraw(false);
if(mCamera!=null){
isPreviewRunning = true;
Camera.Parameters p = mCamera.getParameters();
List<Size> sizes = p.getSupportedPreviewSizes();
Size size = p.getPreviewSize();
width = size.width;
height = size.height;
p.setPreviewFormat(ImageFormat.NV21);
showSupportedCameraFormats(p);
mCamera.setParameters(p);
rgbints = new int[width * height];
mCamera.startPreview();
mCamera.setPreviewCallback(previewCallback);
}
}
}
}
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
Log.d(TAG,"surfaceDestroyed!");
if(CameraActivity.filterMode == CameraActivity.NORMAL_FILTER){
if (mCamera != null) {
mCamera.stopPreview();
isPreviewRunning = false;
}
}else{
synchronized(mSurfaceView){
if(mCamera!=null){
mCamera.setPreviewCallback(null);
mCamera.stopPreview();
isPreviewRunning = false;
}
}
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
Log.d(TAG,"surfaceChanged!");
}
};
/*
* ************************************************************************************
* CAMERA PREVIEW CALLBACK
* ************************************************************************************
*/
Camera.PreviewCallback previewCallback = new Camera.PreviewCallback() {
@Override
public void onPreviewFrame(byte[] data, Camera camera) {
if (!isPreviewRunning)
return;
Canvas resCanvas = null;
if (mHolder == null) {
return;
}
try {
synchronized (mHolder) {
resCanvas = mHolder.lockCanvas(null);
int resCanvasW = resCanvas.getWidth();
int resCanvasH = resCanvas.getHeight();
if(mBitmap == null){
mBitmap = Bitmap.createBitmap (width, height, Bitmap.Config.ARGB_8888);
}
decodeYUV(rgbints, data, width, height);
Canvas canvas = new Canvas(mBitmap);
//Setting the filter
if(camAct.getCustomFilter().equalsIgnoreCase("NORMAL")) ;//don't change the rgb value
if(camAct.getCustomFilter().equalsIgnoreCase("GRAYSCALE")) rgbints = grayscale(rgbints);
if(camAct.getCustomFilter().equalsIgnoreCase("INVERT")) rgbints = invert(rgbints);
if(camAct.getCustomFilter().equalsIgnoreCase("BOOSTRED")) rgbints = boostColor(rgbints,1);
if(camAct.getCustomFilter().equalsIgnoreCase("BOOSTGREEN")) rgbints = boostColor(rgbints,2);
if(camAct.getCustomFilter().equalsIgnoreCase("BOOSTBLUE")) rgbints = boostColor(rgbints,3);
if(camAct.getCustomFilter().equalsIgnoreCase("NOISE")) rgbints = noise(rgbints);
if(camAct.getCustomFilter().equalsIgnoreCase("HUE")) rgbints = hue(rgbints);
if(camAct.getCustomFilter().equalsIgnoreCase("SATURATION")) rgbints = saturation(rgbints);
if(camAct.getCustomFilter().equalsIgnoreCase("ENGRAVE")) rgbints = engrave(rgbints);
if(camAct.getCustomFilter().equalsIgnoreCase("EMBOSS")) rgbints = emboss(rgbints);
// draw the decoded image, centered on canvas
canvas.drawBitmap(rgbints, 0, width, 0,0, width, height, false, null);
resCanvas.drawBitmap (mBitmap, resCanvasW-((width+resCanvasW)>>1), resCanvasH-((height+resCanvasH)>>1),null);
}
} catch (Exception e){
e.printStackTrace();
} finally {
// do this in a finally so that if an exception is thrown
// during the above, we don't leave the Surface in an
// inconsistent state
if (resCanvas != null) {
mHolder.unlockCanvasAndPost(resCanvas);
}
}
}
};
任何帮助非常感谢！
推荐答案
来自其他方法的回调传递到线程的事件循环，调用open（） 。如果这个线程没有事件循环，那么回调被传递到主应用程序事件循环。如果没有主应用程序事件循环，则不传递回调。 来源
Callbacks from other methods are delivered to the event loop of the thread which called open(). If this thread has no event loop, then callbacks are delivered to the main application event loop. If there is no main application event loop, callbacks are not delivered. Source
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